Three dimensional seismic data volumes (sometimes referred to as seismic data volume or seismic cube) comprise a two-dimensional array of acoustic responses of the subsurface which have been collected in a selected area. Acoustic impedance contrasts in the subsurface, which may be associated with lithological boundaries between layers of rock, cause partial reflection of seismic waves travelling through the subsurface. Features in the seismic responses that are caused by such acoustic impedance contrasts are referred to as “seismic events”. In reflection seismology, seismic events correspond to depths of reflected seismic waves.
The three dimensions of a seismic data volume are composed of two lateral dimensions representing geographic locations in the subsurface which can be expressed in or converted to a latitude and longitude, and one depth dimension which can be expressed in or converted to a unit of elevation relative to a standard such as average sea level at the geographic locations. The depth dimension may be represented in units of time, suitably corresponding to two-way travel times of seismic events at various depths, at a plurality of lateral coordinates. The depth dimension may also be represented in units of length, which may be suitable to represent migrated seismic data.
Within a seismic data volume, some events can collectively be attributed to a continuous reflecting surface that spans over a large part of, or the entire, seismic cube. A horizon is an imaginary surface in the seismic data volume, which connects all seismic events that correspond to reflections from a single reflecting surface in the formation.
Seismic interpreters are interested to image events between horizons. Geologically, a horizon is representative of a single geological age. When studying events in seismic data volumes that manifest between horizons, it is useful to study the events in planes that are equidistant from a horizon (so-called horizon-conformant slices) or proportionally defined between two horizons (proportional slices). Either way is an approximation of a section through one geological depth and could reveal basin sedimentary infill and erosive features which help in ascertaining presence and nature of mineral hydrocarbons.
In practice, a computer is needed to display views within a 3D seismic data volume, and views of attribute renderings of the seismic data within the selected slice. Stratal software allows a seismic interpreter to specify one or two horizons and a “distance” (expressed in depth difference) from one of the horizons and, optionally, a slab thickness representing a depth interval band around the slice. It is quite a time consuming process to view sequences of attribute renderings of multiple slices one after another.
It is an object of the invention to improve the user interface with the aim to enhance the speed at which sequences of attribute renderings along multiple slices can be displayed and viewed.